Thin layer chromatography bioautography (using DPPH spray reagent) guided fractionation of Glycyrrhiza glabra led to the isolation of two caffeic acid derivative esters, viz. eicosanyl caffeate (1) and docosyl caffeate (2). The two compounds exhibited potent elastase inhibitory activity, with IC50 values of 0.99μg mL-1 and 1.4μg mL-1 for 1 and 2, respectively. The compounds also showed moderate antioxidant activity in DPPH and ABTS scavenging assays. The results indicate a possible role of caffeic acid derivatives, in addition to flavonoids in the anti-ulcer properties of G. glabra.
Dey, S., Deepak, M., Setty, M., D'Souza, P., Agarwal, A., & Sangli, G. K. (2009). Bioactive caffeic acid esters from Glycyrrhiza glabra. Natural Product Research, 23(18), 1657-1663. https://doi.org/10.1080/14786410802134348